Tomorrow KC goes to the vet --she has been grieving long and loud -- and I just figured it out yesterday.
At night she roams the halls meowing and crying at the top of her little lungs. She used to "patrol" and check on Bear, who slept in on the couch. Sometimes KC (and Missy) would sleep nearby Bear, watching over her.
During the day KC constantly whines for attention, but nothing helps. Then she has these "tears" where she is like a mad cat. She runs the halls, climbs the curtains, the shower curtain, tries to climb the walls ! Just a fury of activity.